He was one of Birmingham’s most feared and secretive criminal figures.

For years Mohammed Suleman Khan , 44, tried to evade the attention of police as he built up a fortune from behind the walls of his Moseley home.

Even to other criminals in Birmingham, he was a shadowy figure known as The General, MSK or Sully, and was rarely seen in public.

To the authorities Khan appeared to have next to nothing on paper. His family home belonged to relatives and only small amounts of money went through his bank accounts.

But while careful to avoid showing any trappings of wealth in the UK, police discovered he had secretly paid for a £2.3 million mansion to be built in Pakistan – complete with library, private cinema, and servant quarters.

A judge described it as Khan’s very own Buckingham Palace when he sentenced the tax fraudster to four years jail in 2013 for cheating the public purse out of almost £450,000 over nine years.

Officers found evidence of huge cash amounts coming into his possession, including £120,000 on one occasion. The tax fraud evidence included 13 banknote wraps, each marked with ‘£1,000’, while he also paid for cars in cash, including £22,000 for a BMW.

Khan did not utter a word during his police interview or court appearances, aside from ‘guilty’

After the original fraud sentencing DCI Bannister had said: “We disputed the amounts earned. Our research was not able to find any business he controlled or owned that was consistent with him being a debt collector within the community.

“We were effectively prosecuting someone based on the evidence about lifestyle and property without having easily obtained evidence.’’

Khan did not utter a word during his police interview or court appearances, aside from ‘guilty’ when he admitted cheating the public revenue at court.

In court, his defence portrayed him as a legitimate businessman who had earned around £400,000 over the nine-year period from debt collecting and other business interests in the UK and abroad.

Police found no evidence of a legitimate debt collecting company and a painstaking investigation proved he had actually netted well over £1 million during that period, without paying the required tax and National Insurance.

Mohammed Suleman Khan's £2.3m palace under construction - August 2011

Officers found evidence of huge cash amounts coming into the possession of Khan, including £120,000 on one occasion.

The tax fraud evidence included 13 banknote wraps, each marked with ‘£1,000’, while it was also discovered he had paid for cars in cash, including £22,000 for a black BMW.

It was during a search of Khan’s Birmingham home after his arrest that plans for the ‘palace’ in the Attock region of Pakistan were discovered.

With no jurisdiction in that country, detectives used the plans and a Google Earth photo to show the sprawling scale of the building. The outer shell and roof of the building had been completed by Khan at a cost of £893,000. If completed the property would have valued at £2.3 million.

Khan had pleaded guilty to cheating the public revenue at an appearance at Birmingham Crown Court in November 2013.

His honour Judge Andrew Menary QC agreed Khan was living beyond legitimate means, the most obvious evidence of that being his Pakistan property. He said: “It is enormous... with dozens of rooms, a library, servant quarter, cinema, underground parking and guard rooms. It is the size of Buckingham Palace.’’

Mohammed Suleman Khan's £2.3m palace under construction - 2010

Police said at the time that they hoped the sentence would reverberate around the criminal fraternity.

DCI Bannister said: “The sentence handed out sends a clear message to all members of the community that evasion of tax and National Insurance are serious criminal offences.

“No matter your standing within the community, police and other agencies such as Her Majesty’s Revenue and Customs will seek to investigate and where appropriate prosecute individuals who are perceived or seen to be living a lifestyle or own property inconsistent with legitimately earned income.’’

Chief Superintendent Alex Murray, responsible for policing in east Birmingham, said at the time: “The message from West Midlands Police is that we will stop you, whether that is through criminal law, through Revenue and Customs, the Department for Work and Pensions or others. Communities are fed up of people thinking they are above the law and are increasingly standing up to be counted.”

Shahlam Khan, Mohammed Mughal and Shokut Zuman, L to R.

Last August Khan’s brothers Shahalam Khan , of Station Road, Kings Heath, and Shokut Zuman, of Selly Oak Road, Bournville, were convicted of conspiracy to defraud, along with Zuman’s wife Samiah Hanna, of Arley Road, Selly Oak.

Co-accused Arshid Khan, of Banks Road, Small Heath, and crooked broker Mohammed Mughal, of Chester Road, Bournville, were also convicted of conspiracy to defraud.

The gang built up a valuable property portfolio by “taking advantage of a buoyant property market” between 2003 and 2010. They made false declarations to obtain mortgages they would otherwise have been refused.

They were brought to justice at Birmingham Crown Court. Shahalam Khan, 46, received a five-year term after also being convicted of benefit fraud.

Shokut Zuman.

Shokut Zuman, 42, received a four and half year sentence, while Hannah, 45, received a two-year suspended sentence.

Arshid Khan, 46, was jailed for five years while crooked broker Mohammed Mughal, 66, was jailed for four and a half years.

The gang used forged financial documents to bag mortgages on 21 properties in the Bournville, Selly Oak and Moseley areas. The houses were renovated then rented, mainly to students, allowing the gang to earn huge amounts in rent.

An appeal was rejected last week.

Their lawyers asked for permission to appeal on a broad range of grounds, claiming their convictions were unfair. Amongst other things, complaints were made about a juror having left the jury room during deliberations.

It was also claimed that the defence case was prejudiced by a ten-day delay between closing submissions and jurors retiring to consider their verdicts.

That delay was caused by one of the jurors having gone away for a week at the end of the trial on a pre-booked holiday, the court heard.